Variable diameter trigger wire

ABSTRACT

A self-expanding medical device delivery system includes a plurality of trigger wires. The trigger wires retain a self-expanding medical device by forming a bend about structural members located on the proximal portion of the medical device. The proximal portions of the trigger wires have a greater diameter than the distal portions of the trigger wires to provide increased bending strength. An operator releases the self-expanding medical device by withdrawing the trigger wires in the distal direction. In some embodiments, a small portion at the proximal end of the trigger wire has a smaller diameter than the rest of the proximal portion. In other embodiments, the proximal and distal portions of the trigger wire each have a greater diameter than the center of the trigger wire.

BACKGROUND

The present invention relates generally to medical device deploymentsystems and more particularly to trigger wires used in low-profiledelivery systems for self-expanding medical devices.

The use of trigger wires in delivery systems to retain and releaseself-expanding medical devices is well-known in the art. As used in thepresent application, “proximal” and “distal” are defined relative to theheart. Trigger wires typically retain a self-expanding medical device byforming a bend around a portion of the self-expanding medical device,and release the self-expanding medical device when the trigger wire iswithdrawn proximally through the delivery system so that the triggerwire no longer forms a bend about the medical device. Known triggerwires are of constant cross-section. Thus, trigger wires must restrainthe self-expanding medical device during delivery, be capable of beingwithdrawn through the delivery system, and provide an adequateconnection to a handle at the distal end of the trigger wire.

Different levels of bending and tensile strength are required for eachof the functions a trigger wire must perform. For example, a certainlevel of bending strength is required at the proximal portion of thetrigger wire where the trigger wire retains the medical device, and acertain level of bending strength is also required at the distal portionof the trigger wire where the trigger wire connects to the handle. Thecenter portion of the trigger wire only requires adequate tensilestrength as an operator withdraws the trigger wire through the deliverysystem.

Delivery devices for self-expanding medical devices are typicallyadvanced through a body vessel to a treatment site. Thus, it isadvantageous to minimize the size of delivery devices to allow operatorsto place self-expanding medical devices in smaller body vessels, and tominimize potential trauma to body vessels as the delivery device passesthrough. A lower-profile device is also advantageous because it iseasier to navigate through tortuous vasculature. Additionally, alower-profile delivery device is advantageous to allow an operator toposition or use other medical devices in the body vessel simultaneouslywith the delivery device.

BRIEF SUMMARY

The invention may include any of the following aspects in variouscombinations and may also include any other aspect described below inthe written description or in the attached drawings.

A self-expanding medical device delivery system includes a deliverysheath and an inner member, where the inner member is disposed withinthe lumen of the delivery sheath. A plurality of first openings and aplurality of second openings are disposed on the proximal portion of theinner member. A self-expanding medical device is also disposed upon theproximal portion of the inner member. The proximal portion of theself-expanding medical device includes exposed structural members. Aplurality of trigger wires is disposed within the lumen of the innermember, each trigger wire exiting the lumen of the inner member througha first opening and re-entering the lumen through a second opening,thereby forming a bend. The proximal portion of the trigger wires has agreater diameter than the distal portion of the trigger wires. The bendsformed by the trigger wires engage and compress the exposed structuralmembers of the self-expanding medical device toward the inner member,retaining the self-expanding medical device on the inner member. Todeploy the self-expanding medical device, an operator withdraws thetrigger wires through the lumen of the inner member until the proximalportions of the trigger wires no longer pass through the secondopenings.

The diameter of the proximal portion of the trigger wire may be fivetimes the diameter of the distal portion of the trigger wire.

The self-expanding medical device deployed may be a stent graft or aself-expanding stent.

The delivery system may also include a guide wire which passes throughthe lumen of the delivery sheath and extends beyond the most proximalportion of the inner member.

The first and second openings may be positioned at varying distancesfrom the distal end of the inner member.

The Proximal End of the Inner Member May be Flared Outward.

The proximal end of the trigger wire may have a smaller diameter thanthe proximal portion of the trigger wire.

Alternatively, the plurality of trigger wires may have a proximalportion, a distal portion, and a center portion. The diameter of theproximal portion of the trigger wire is greater than the diameter of thecenter portion of the trigger wire. The diameter of the distal portionof the trigger wire is also greater than the diameter of the centerportion of the trigger wire. The distal portions of the trigger wiresare attached to a handle configured to withdraw the trigger wires in thedistal direction through the lumen of the inner catheter to release theself-expanding medical device.

The diameter of the distal portion of the trigger wire may be five timesthe diameter of the center portion of the trigger wire.

The proximal end of the trigger wire may have a smaller diameter thanthe proximal portion of the trigger wire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section view of the self-expanding medicaldevice delivery system and one of the plurality of trigger wirespartially deployed.

FIG. 2 is a longitudinal view of one embodiment of the trigger wires.

FIG. 3 is a partial longitudinal view of the self-expanding medicaldevice delivery system wherein the self-expanding medical device ispartially deployed and constrained by a plurality of trigger wires.

FIG. 4 is a longitudinal section view of the self-expanding medicaldevice delivery system and one of the plurality of trigger wires in itsdelivery configuration.

FIG. 5 is a longitudinal section view of the partially-deployedself-expanding medical device delivery system with a flared portion atthe proximal end of the inner member.

FIG. 6 is a longitudinal view of another embodiment of the plurality oftrigger wires wherein the proximal ends of the trigger wires have asmaller diameter than the diameter of the proximal portions of thetrigger wires.

FIG. 7 is a longitudinal section view of self-expanding medical devicedelivery system with the trigger wires shown in FIG. 6.

FIG. 8 is a longitudinal view of the partially deployed self-expandingmedical device delivery system where the trigger wires have a largerdiameter at the proximal and distal ends.

FIG. 9 is a longitudinal view of the trigger wires where the triggerwires have a larger diameter at the proximal and distal ends.

FIG. 10 is a longitudinal view of the trigger wires where the triggerwires have a smaller diameter at the proximal end and the center, and alarger diameter at the proximal and distal portions of the triggerwires.

FIG. 11 is a longitudinal section view of self-expanding medical devicedelivery system employing the trigger wires shown in FIG. 10.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERREDEMBODIMENTS

Referring now to the figures, a self-expanding medical device deliverysystem is shown. A delivery sheath 4 has a lumen 10. An inner member 12is disposed within the lumen 10 of the delivery sheath 4. A plurality offirst openings 20 and a plurality of second openings 22 are disposedupon the proximal portion 14 of inner member 12. Each of the pluralityof second openings 22 is disposed proximally of one of the plurality offirst openings 20.

A self-expanding medical device 24 is disposed about the proximalportion 14 of inner member 12. The proximal end 26 of self-expandingmedical device 24 includes exposed structural members 28. Self-expandingmedical device 24 may be a self-expanding stent, stent graft, or anyother self-expanding medical device that includes exposed structuralmembers.

A plurality of trigger wires 30 is disposed within the lumen 18 of innermember 12. Trigger wire 30 has a proximal portion 32 and a distalportion 34. The proximal portion 32 of trigger wire 30 has a greaterdiameter than the diameter of distal portion 34. The trigger wire 30exits the lumen 18 of inner member 12 through a first opening 20 andre-enters the lumen 18 of inner member 12 through a second opening 22such that the proximal portion 32 of trigger wire 30 forms a bend 36.The transition between the first and second diameters preferably occurswithin a first opening 20. Bend 36 engages and compresses exposedstructural members 28 toward inner member 12, retaining self-expandingmedical device 24 in position on the proximal portion 14 of inner member12.

Trigger wire 30 may be tapered using any of a number of suitablemanufacturing methods. For example, the distal portion 34 of the triggerwire 30 could be ground to reduce its diameter. Another method fortapering trigger wire 30 would be to overlay a thin cannula over theproximal portion 32 of trigger wire 30. Other methods not described heremay also be used.

Trigger wire 30 is configured to be withdrawn in the distal directionthrough the lumen 18 of inner member 12. To deploy self-expandingmedical device 24, an operator advances self-expanding medical devicedelivery system 2 through a body vessel to a desired deployment site.The device is advanced in its delivery configuration as shown in FIG. 4.As the operator advances the device to the deployment site, the deliverysheath 4 covers the inner member 12 and self-expanding medical device24. After positioning self-expanding medical device 24 at the desiredlocation, the operator withdraws the delivery sheath 4 in the distaldirection to expose the proximal portion 14 of inner member 12 and theself-expanding medical device 24 as shown in FIG. 1. The operator thenwithdraws trigger wire 30 through lumen 18 of inner member 12. Theoperator may withdraw each of the plurality of trigger wires 30individually through the lumen 18 of inner member 12 or withdraw each ofthe plurality of trigger wires 30 through the lumen 18 of inner member12 at different rates. As trigger wire 30 is withdrawn, proximal portion32 of trigger wire 30 is pulled out of second opening 22 until proximalportion 32 no longer passes through second opening 22. When proximalportion 32 is removed from second opening 22, exposed structural members28 are no longer restrained by proximal portion 32 of trigger wire 30.The exposed structural members 28 expand outward to anchorself-expanding medical device 24 at the location desired by theoperator.

This configuration allows the use of a delivery sheath 4 and innermember 12 with smaller diameters than used with a trigger wire 30 of aconstant diameter. Because the proximal portion 32 of trigger wire 30 isdisposed proximally of the proximal end 26 of self-expanding medicaldevice 24, self-expanding medical device 24 may be more fullycompressed. Additionally, inner member 12 need only be large enough toallow the operator to withdraw one trigger wire 30 through the lumen 18of inner member 12.

As shown in FIG. 1, the self-expanding medical device delivery system 2may include the use of a guide wire 38. The self-expanding medicaldevice delivery system 2 may also include a bulbous tip 46, as shown inFIG. 8.

As shown in FIG. 3, the self-expanding medical device 24 may be a stentgraft. A plurality of trigger wires 30 is shown retaining theself-expanding medical device 24 on inner member 12, as shown in FIG. 3.The first openings 20 and second openings 22 may be staggered such thateach of the plurality of trigger wires 30 enters and exits the innermember 12 at different longitudinal positions. This allows the innermember 12 to be of a smaller diameter, because each of the proximalportions 32 of the plurality of trigger wires 30 are staggered such thatat least one proximal portion 32 does not lie parallel to at least oneother proximal portion 32 as the plurality of trigger wires 30 iswithdrawn.

Proximal portion 32 of trigger wire 30 has a diameter that can provideadequate strength to retain self-expanding medical device 24. Thus, thediameter of the proximal portion 32 is dependent upon the type ofself-expanding medical device 24 used. In the embodiment shown in FIG.3, self-expanding medical device 24 is a stent graft. The diameter ofthe proximal portion 32 required to retain a common stent graft mayrange from 2 to 5 times the diameter of the distal portion 34. Theproximal portion 32 of trigger wire 30 must be long enough to form abend 36 around the exposed structural members 28. For a typical stentgraft, the proximal portion 32 may be 1 to 2 inches long.

In contrast, distal portion 34 of trigger wire 30 only requires adequatetensile strength to withdraw trigger wire 30 through lumen 18 of innermember 12. Thus, the required diameter of distal portion 34 is less thanthe diameter of proximal portion 32. By providing a trigger wire 30 witha distal portion 34 of lesser diameter than proximal portion 32, asmaller inner member 12 may be used. In turn, this allows the use of asmaller diameter delivery sheath 4, which would result in aself-expanding medical device delivery system 2 with a lower profile.The distal portion 34 of trigger wire 30 must be long enough to extendfrom the deployment site through the vasculature and outside the body tothe operator. Thus, the distal portion 34 may be up to 3 feet long.

FIG. 5 illustrates another embodiment of the self-expanding medicaldevice delivery system 2. In this embodiment, the proximal end 42 of theproximal portion 14 of the inner member 12 is flared outward to receivethe proximal portion 32 of trigger wire 30. Because the flared proximalend 42 is proximal to the self-expanding medical device 24, a smallerdelivery sheath 4 may be used.

FIGS. 6 and 7 illustrate another embodiment of the trigger wire 30. Inthis embodiment, the proximal end 44 of the trigger wire 30 has asmaller diameter than the diameter of the proximal portion 32 of triggerwire 30. The proximal end 44 of trigger wire 30 is the portion oftrigger wire 30 that re-enters inner member 12 through the secondopening 22. The transition between the smaller diameter of proximal end44 and the larger diameter of proximal portion 32 preferably occurswithin the second opening 22.

FIGS. 8 and 9 illustrate another embodiment of the self-expandingmedical device delivery system 2. In this embodiment, the plurality oftrigger wires 130 is connected to a handle 40 at the distal end of theself-expanding medical device delivery system 2. FIG. 5 shows a rotaryhandle 40, but handle 40 may be any of several well-known devices usedto pull trigger wires and other elongate devices distally through astent delivery system, including push-pull devices, rotary devices, anddevices that employ a pistol grip. The handle 40 may also be configuredto take up each of the plurality of trigger wires 30 at different rates.

Trigger wire 130 has a proximal portion 132, a distal portion 134, and acenter portion 136. Proximal portion 132 has a first diameter, distalportion 134 has a second diameter, and center portion 136 has a thirddiameter. The first diameter of proximal portion 132 is greater than thethird diameter of center portion 136. The second diameter of distalportion 134 is also greater than the third diameter of center portion136. The first diameter of proximal portion 132 may be greater than,equal to, or lesser than the second diameter of distal portion 134,depending on the diameters required to provide adequate bending strengthrequired. As noted above, the adequate bending strength for the proximalportion 132 varies with the self-expanding medical device 24 used. Thediameter of the proximal portion 132 required to retain a common stentgraft may range from 2 to 5 times the diameter of the center portion136. The proximal portion 132 of trigger wire 130 must be long enough toform a bend around the exposed structural members 28. For a typicalstent graft, the proximal portion 132 may be 1 to 2 inches long.

Additional bending strength is required at the distal portion 134 oftrigger wire 130 to ensure a secure connection between distal portion134 of trigger wire 130 and handle 40. The adequate bending strength forthe distal portion 134 varies with the handle 40 used. The length ofdistal portion 134 also varies based on the type of handle 40 used.

Center portion 136 of trigger wire 130 only requires adequate tensilestrength to withdraw trigger wire 130 through lumen 18 of inner member12. Thus, the required diameter of center portion 136 is less than thediameter of proximal portion 132 and distal portion 134. A trigger wire130 with a decreased diameter in center portion 136 is desirable tolower the profile of self-expanding medical device delivery system 2.The center portion 136 of trigger wire 130 must be long enough to extendfrom the deployment site through the vasculature and to the distalportion 134. Thus, the center portion 136 may be up to 3 feet long.

The transition between the smaller diameter of center portion 136 andthe larger diameter of proximal portion 132 preferably occurs within afirst opening 20.

FIGS. 10 and 11 illustrate another embodiment of trigger wire 130. Inthis embodiment, the trigger wire 130 has proximal portion 132, a distalportion 134, and a center portion 136. The proximal portion 132 has aproximal end 144. The proximal portion 132 has a first diameter, distalportion 134 has a second diameter, center portion 136 has a thirddiameter, and the proximal end 144 of the proximal portion 132 has afourth diameter. The first diameter of proximal portion 132 is greaterthan the third diameter of center portion 136. The second diameter ofdistal portion 134 is also greater than the third diameter of centerportion 136. The first diameter of proximal portion 132 is greater thanthe fourth diameter of the proximal end 144 of proximal portion 132. Thefirst diameter of proximal portion 132 may be greater than, equal to, orlesser than the second diameter of distal portion 134, depending on thediameters required to provide adequate bending strength. The thirddiameter of center portion 136 may be greater than, equal to, or lesserthan the fourth diameter of the proximal end 144 of the proximal portion132, depending on the diameters required to provide adequate tensilestrength.

As shown in FIG. 11, the proximal end 144 of trigger wire 130 is theportion of trigger wire 130 that re-enters inner member 12 through oneof the plurality of second openings 22. The transition between thesmaller diameter of proximal end 144 and the larger diameter of proximalportion 132 preferably occurs within a second opening 22.

While preferred embodiments of the invention have been described, itshould be understood that the invention is not so limited, andmodifications may be made without departing from the invention. Thescope of the invention is defined by the appended claims, and alldevices that come within the meaning of the claims, either literally orby equivalence, are intended to be embraced therein. Furthermore, theadvantages described above are not necessarily the only advantages ofthe invention, and it is not necessarily expected that all of thedescribed advantages will be achieved with every embodiment of theinvention.

1. A self-expanding medical device delivery system comprising: adelivery sheath with a lumen and a proximal portion; an inner memberpartially disposed within said lumen of said delivery sheath, said innermember having a lumen and a proximal portion and a distal end, saidproximal portion of said inner member having a plurality of firstopenings and a plurality of second openings, where said second openingis disposed proximally of said first opening; a self-expanding medicaldevice disposed about said proximal end of said inner member, saidself-expanding medical device having a proximal end, said self-expandingmedical device having exposed structural members on said proximal end ofsaid self-expanding medical device; a plurality of trigger wirespartially disposed within said lumen of said inner member, said triggerwire having a proximal portion with a first diameter and distal portionwith a second diameter, where said first diameter is greater than saidsecond diameter; said plurality of trigger wires exits said lumen ofsaid inner member through one of said plurality of first openings andre-entering said lumen of said inner member through one of saidplurality of second openings such that said proximal portion of saidtrigger wire forms a bend, said bend of said trigger wire engaging saidexposed structural members and such that said exposed structural membersare compressed and said self-expanding medical device is retained bysaid proximal portion of said trigger wire; and said plurality oftrigger wires configured to be withdrawn in the distal direction throughsaid lumen of said inner member such that said trigger wires disengagesaid exposed structural members and release said self-expanding medicaldevice.
 2. The delivery system of claim 1 wherein said first diameter ofsaid trigger wire is 2 to 5 times greater than said second diameter ofsaid trigger wire.
 3. The delivery system of claim 1 wherein saidself-expanding medical device is a stent graft.
 4. The delivery systemof claim 1 wherein said self-expanding medical device is aself-expanding stent.
 5. The delivery system of claim 1 furthercomprising a guide wire partially disposed within said delivery sheathwith a proximal end, said proximal end of said guide wire extendingbeyond the most proximal portion of said inner member.
 6. The deliverysystem of claim 1 having a delivery configuration, wherein said proximalportion of said trigger wire lies proximal of said first opening in saiddelivery configuration.
 7. The delivery system of claim 1 wherein eachof said plurality of first openings is positioned a varying distancefrom said distal end of said inner member and each of said plurality ofsecond openings is positioned a varying distance from said distal end ofsaid inner member.
 8. The delivery system of claim 1 wherein saidproximal portion of said inner member has a proximal end, wherein saidproximal portion of said inner member is flared outward.
 9. The deliverysystem of claim 1 wherein said proximal portion of said trigger wire hasa proximal end, said proximal end having a third diameter, wherein saidfirst diameter is greater than said third diameter.
 10. A self-expandingmedical device delivery system comprising: a delivery sheath with alumen and a proximal portion; an inner member partially disposed withinsaid lumen of said delivery sheath, said inner member having a lumen anda proximal portion and a distal end, said proximal portion of said innermember having a plurality of first openings and a plurality of secondopenings, where said second opening is disposed proximally of said firstopening; a self-expanding medical device disposed about said proximalend of said inner member, said self-expanding medical device having aproximal end, said self-expanding medical device having exposedstructural members on said proximal end of said self-expanding medicaldevice; a plurality of trigger wires partially disposed within saidlumen of said inner member, said trigger wires having a proximal portionwith a first diameter, a distal portion with a second diameter, and acenter portion with a third diameter, where said first diameter isgreater than said third diameter and said second diameter is greaterthan said third diameter; each of said plurality of trigger wires exitssaid lumen of said inner member through one of said plurality of onefirst openings and re-entering said lumen of said inner member throughone of said plurality of second openings such that said proximal portionof said trigger wires forms a bend, said bend of said trigger wiresengaging said exposed structural members and such that said exposedstructural members are compressed and said self-expanding medical deviceis retained by said proximal portions of said trigger wires; and ahandle, said distal portion of said trigger wires connected to saidhandle, said handle configured to withdraw said trigger wires in thedistal direction through said lumen of said inner member such that saidtrigger wires disengage said exposed structural members and releasessaid self-expanding medical device.
 11. The delivery system of claim 10wherein said first diameter of said trigger wire is 2 to 5 times greaterthan said third diameter of said trigger wire.
 12. The delivery systemof claim 10 wherein said second diameter of said trigger wire is 2 to 5times greater than said third diameter of said trigger wire.
 13. Thedelivery system of claim 10 wherein said self-expanding medical deviceis a stent graft.
 14. The delivery system of claim 10 wherein saidself-expanding medical device is a self-expanding stent.
 15. Thedelivery system of claim 10 further comprising a guide wire partiallydisposed within said inner member with a proximal end, said proximal endof said guide wire extending beyond the most proximal portion of saidinner member.
 16. The delivery system of claim 10 having a deliveryconfiguration, wherein said proximal portion of said trigger wire liesproximal of said first opening in said delivery configuration.
 17. Thedelivery system of claim 10 wherein each of said plurality of firstopenings is positioned a varying distance from said distal end of saidinner member and each of said plurality of second openings is positioneda varying distance from said distal end of said inner member.
 18. Thedelivery system of claim 10 wherein said proximal portion of said innermember has a proximal end, said proximal portion of said inner memberflared outward such that said proximal end has the largest diameter. 19.The delivery system of claim 10 wherein said proximal portion of saidtrigger wire has a proximal end, said proximal end having a fourthdiameter, wherein said first diameter is greater than said fourthdiameter.